Design of Navigation Computer Tester Based on AT91RM9200

Abstract: This paper introduces a design of a navigation computer tester based on AT91RM9200. The tester can receive data from multiple input data interfaces, process them by computer, and then output the results through the output data interface. In addition, the navigation tester based on AT91RM9200 can test two sets of navigation computers conveniently and quickly.

0 Introduction

The navigation computer is a component of the strapdown combined navigation assembly, which can receive data from multiple input data interfaces and output the results through the output data interface. In order to verify the functions and performance indicators of the navigation computer, the test instrument can be used to complete the detection and testing of the navigation computer. The overall development goal of the navigation computer test instrument is to be able to conveniently and quickly test the two sets of navigation computers, including the rate test of multiple interfaces of the navigation computer, the correctness and integrity test of interface transmission data, and the test of the navigation computer data processing DSP.

1 System composition

This navigation computer test instrument is mainly composed of two parts: the test module and the display control module. The test module mainly includes the test interface and the test unit; the display control module is the input and output device of the navigation computer test instrument, mainly including the host computer processing unit and the display unit. Its specific composition is shown in Figure 1.

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2 Test Module

The test module is mainly used to test the working status and performance of the navigation computer, including the test of each interface of the navigation computer and the test of the DSP processing performance. The test module mainly includes the test interface and the test unit. In order to meet the requirements of testing two sets of navigation computers at the same time and to facilitate the upgrade, this design considers a one-to-one test mode. Figure 2 shows the block diagram of the test module for a set of navigation computers.

In order to ensure that all interfaces of the two navigation computers can work at the required speed at the same time, two processors can be selected to implement one-to-one testing to ensure its real-time performance. The processor of the test part can be selected from Atmel's AT91RM9200 as the central control part of the test instrument. Its two processors have the same functions. Now take one of them as an example to illustrate, its main functions include:

(1) Send data at the required rate and interrupt the reception of data from two RS232, nine RS422A, and one RS429 (1 receive, 2 transmit) data communication interfaces, while unloading frames and testing data transmission interfaces.

Port rate, data correctness and data integrity;

(2) The test results should be connected to the display part through the RS232 interface and displayed in real time;

(3) Expanding input and output interfaces through programmable logic devices;

(4) Data interaction between control and display part;

(5) Control the data interaction between the program and the data storage.

This article uses Ahera's CycloneII series chip EP2C80208C6 to complete the expansion of RS422 interface and RS429 interface. EP2C8Q208C6 device is a high-density, high-performance EEPROM device based on ATERA's second-generation MAX architecture, and its operating clock frequency is up to 260 MHz.

The main functions of EP2C8Q208C6 are to realize system reset and clock distribution, data bus expansion and external interface expansion, etc.

3 Display module

The display control module is the input and output device of the navigation computer tester. It is responsible for the function parameter input, setting and system control during the navigation computer test process. The hardware composition of the display control module is shown in Figure 3.

The core of the display control module is the ARM processor, which mainly completes LCD display, touch screen control, communication control of the test module, etc. The ARM processor can choose the embedded ARM processor S3C2440 of SAMSUNG, and the LCD can use a 7-9 inch touch screen liquid crystal display, and use two RS232 serial ports as the data transmission interface with test module 1 and test module 2. The upper processing unit controls the test module through these two serial ports.

The main function of the display part is to realize human-computer interaction, specifically to control the software operation of the test part, to exchange data with the test part, and to display the test results. Other external interfaces of the display part can enrich the functions of the tester. Among them, the result display part can be used to display the test results in real time, and the interface design needs to facilitate human-computer interaction: the control part mainly includes power supply control, reset control, test equipment selection control, etc.; the function selection includes data interface rate test, data transmission correctness test, data transmission integrity test and solution platform correctness test, etc. [page]

4 Test objectives and test principles

According to the development objectives, the main test items implemented by this navigation tester are: 1. Testing the transmission rate of each interface; 2. Implementing data interaction with the navigation board according to the required rate and baud rate of each interface of the navigation computer in the development indicators, and the tester monitors the status of each interface in real time; 3. Testing the correctness and integrity of data transmitted by each interface; 4. Verifying whether the data received by each interface during this period is complete within a certain period of time (assuming 2 seconds) through a certain algorithm. This function can be designed in the software as follows: within t seconds, sum the data received by each interface, and the sum of the data received by the jth channel within t seconds is:

Among them, represents the i-th data received by the j-th channel; j represents the serial number of each interface of the navigation board; M is the number of data sent by the channel each time. N is the number of times the interface receives data within t seconds, and vj represents the receiving rate of the interface;

The last step is to test the working status of DSP. Generally, after the navigation board is powered on, the program burned inside DSP will run self-test first (the LED light flashes to indicate normal), and then the DSP internal operation program will be simulated using DSP simulator. The experimental algorithm is as follows:

Within a certain time t (assuming t = 1 second), the sum Sj of the data received by each interface is sent to the DSP for simple calculation, where:

In the formula, represents the i-th data received by the j-th channel; j represents the serial number of each interface of the navigation board; M is the number of data sent by the channel each time. Nj is the number of times the interface receives data within t seconds, and vj represents the receiving rate of the interface.

The DSP performs a 2-times multiplication operation on the received Sj and obtains it, and then sends the result back to the tester.

5 Workflow

The test module is the central module of the navigation computer tester, which is responsible for testing the navigation computer and transmitting the test results to the host computer for display according to the protocol requirements. Figure 4 shows the workflow of the test module.

6 Conclusion

This paper introduces a design of a navigation computer tester based on AT91RM9200. The tester can receive data from multiple input data interfaces, and after the computer performs calculations, the results are output by the output data interface. This method can conveniently and quickly test two sets of navigation computers. At present, this system has been successfully applied in practice, proving that the system functions can fully meet actual needs.